13 Jun 2022
13 Jun 2022
Status: this preprint is currently under review for the journal GChron.

10Be age control of glaciation in the Beartooth Mountains, USA from the latest Pleistocene through the Holocene

Aaron M. Barth1, Elizabeth G. Ceperley2, Claire Vavrus2, Shaun A. Marcott2, Jeremy D. Shakun3, and Marc W. Caffee4,5 Aaron M. Barth et al.
  • 1Department of Geology, Rowan University, Glassboro, NJ, USA
  • 2Department of Geoscience, University of Wisconsin – Madison, Madison, WI, USA
  • 3Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, MA, USA
  • 4Department of Physics and Astronomy, Purdue University, West Lafayette, IN, USA
  • 5Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, USA

Abstract. Alpine glaciers in the western United States are often associated with late-Holocene Little Ice Age (LIA) advances. Yet, recent studies have shown many of these glacial landforms are remnants of latest-Pleistocene retreat with only the most cirque-proximal moraines preserving LIA activity. Additionally, the timing and magnitude of glacial advances during the Neoglacial-LIA interval remains uncertain with presumed maximum extents occurring during the LIA driven by lower Northern Hemisphere insolation levels. Here we present 10Be surface exposure ages from a glacial valley in the Beartooth Mountains of Montana and Wyoming, United States. These new data constrain the presence of the glacier within 2–3 km of the cirque headwalls by the end of the Pleistocene with implications for large-scale retreat after the Last Glacial Maximum. Cirque moraines from two glaciers within the valley preserve a late-Holocene readvance with one reaching its maximum prior to 2.1 ± 0.2 ka and the other 0.2 ± 0.1 ka. Age variability among the moraines demonstrates that not all glaciers were largest during the LIA and presents the possibility of regional climate dynamics controlling glacial mass balance.

Aaron M. Barth et al.

Status: open (until 28 Jul 2022)

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  • RC1: 'Comment on gchron-2022-17', Anonymous Referee #1, 04 Jul 2022 reply

Aaron M. Barth et al.

Aaron M. Barth et al.


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Short summary
Deposits left behind by past glacial activity provide insight into the previous size and behavior of glaciers, and act as another line of evidence for past climate. Here we present new age control for glacial deposits in the mountains of Montana and Wyoming, United States. While some deposits indicate glacial activity within the last 2000 years, others are shown to be older than previously thought, thus redefining the extent of regional Holocene glaciation.